Method and apparatus for uplink power control in a multicarrier wireless communication system

ABSTRACT

The described apparatus and methods may include a controller configured to determine power required for at least one of a plurality of carriers, and generate at least one of a plurality of power control commands for at least one of the plurality of carriers based on the determination.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application is a divisional of U.S. patent application Ser.No. 12/772,902, entitled “METHOD AND APPARATUS FOR UPLINK POWER CONTROLIN A MULTICARRIER WIRELESS COMMUNICATION SYSTEM” filed May 3, 2010 andclaims priority to Provisional Application No. 61/175,405 entitled“UPLINK POWER CONTROL IN MULTICARRIER OPERATION” filed May 4, 2009, andassigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND

Field

The present disclosure relates generally to wireless communicationsystems. More specifically, the present disclosure relates to a methodand apparatus for uplink power control in a multicarrier wirelesscommunication system.

Introduction

Wireless communication systems are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, etc. These systems may be multiple-access systems capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include Code Division Multiple Access (CDMA)systems, Time Division Multiple Access (TDMA) systems, FrequencyDivision Multiple Access (FDMA) systems, 3GPP Long Term Evolution (LTE)systems, orthogonal Frequency Division Multiple Access (OFDMA) systems,and Single-Carrier FDMA (SC-FDMA) systems.

In communication systems where multiple uplink and downlink carriers arepresent, certain rules should be defined specifying power control formultiple uplink carriers. While in LTE Release 8 there may be only oneuplink paired with one downlink, and the uplink power control isconfigured for controlling transmit power of the channels on the oneuplink carrier, such a solution is inapplicable to multicarrier systems(e.g., LTE-Advanced) having multiple uplink and downlink carrierconfigurations.

Accordingly, there exists a need m the art for a method and apparatusthat provide uplink control for multiple uplinks in multicarriersystems.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

According to an aspect of the disclosure, a wireless communicationapparatus may include a controller configured to determine powerrequired for at least one of a plurality of carriers, and generate atleast one of a plurality of power control commands for at least one ofthe plurality of carriers based on the determination.

According to another aspect of the disclosure, a method for wirelesscommunication may include determining power required for at least one ofa plurality of carriers, and generating at least one of a plurality ofpower control commands for at least one of the plurality of carriersbased on the determination.

According to a further aspect of the disclosure, an apparatus mayinclude means for determining power required for at least one of aplurality of carriers, and means for generating at least one of aplurality of power control commands for at least one of the plurality ofcarriers based on the determination.

According to yet a further aspect of the disclosure, a computer programproduct may include a computer-readable medium including code fordetermining power required for at least one of a plurality of carriers,and code for generating at least one of a plurality of power controlcommands for at least one of the plurality of carriers based on thedetermination.

According to yet a further aspect of the disclosure, a wirelesscommunication apparatus may include a controller configured to decodepower control commands for at least one of a plurality of carriers, anddistribute power among the at least one of the plurality of carriersbased on the power control commands.

According to yet a further aspect of the disclosure, a method forwireless communication may include decoding power control commands forat least one of a plurality of carriers, and distributing power amongthe at least one of the plurality of carriers based on the power controlcommands.

According to yet a further aspect of the disclosure, an apparatus mayinclude means for decoding power control commands for at least one of aplurality of carriers, and means for distributing power among the atleast one of the plurality of carriers based on the power controlcommands.

According to yet a further aspect of the disclosure, a computer programproduct may include a computer-readable medium including code fordecoding power control commands for at least one of a plurality ofcarriers, and code for distributing power among the at least one of theplurality of carriers based on the power control commands.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 illustrates aspects of a wireless communication system;

FIG. 2 illustrates a communications system including an uplink and adownlink between a base station and an access terminal;

FIG. 3 illustrates some aspects of a protocol stack for a communicationssystem;

FIG. 4 illustrates a radio frame structure and a resource grid showing aresource block and resource elements;

FIG. 5 illustrates an example of a multicarrier system that facilitatesuplink power control in a wireless communication environment;

FIG. 6 illustrates an example of uplink/downlink pairing with an anchorcarrier;

FIG. 7 illustrates an example of an access terminal that facilitatesuplink power control in a multicarrier communications system;

FIG. 8 is a block diagram of an example base station that facilitatesuplink power control in a multicarrier communications system;

FIG. 9 is a flow chart illustrating an example of a process for uplinkpower control in a multicarrier communications system from an accessterminal perspective;

FIG. 10 is a flow chart illustrating an example of a process for uplinkpower control in a multicarrier communications system from a basestation perspective;

FIG. 11 is an illustration of an example system that facilitates uplinkpower control in a multicarrier communications system; and

FIG. 12 is an illustration of an example system that facilitates uplinkpower control in a multicarrier communications system.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution.

For example, a component may be, but is not limited to being, a processrunning on a processor, a processor, an object, an executable, a threadof execution, a program, and/or a computer. By way of illustration, bothan application running on a computing device and the computing devicecan be a component. One or more components can reside within a processand/or thread of execution and a component may be localized on onecomputer and/or distributed between two or more computers. In addition,these components can execute from various computer readable media havingvarious data structures stored thereon. The components may communicateby way of local and/or remote processes such as in accordance with asignal having one or more data packets, such as data from one componentinteracting with another component in a local system, distributedsystem, and/or across a network such as the Internet with other systemsby way of the signal.

Furthermore, various aspects are described herein in connection with aterminal, which can be a wired terminal or a wireless terminal Aterminal can also be called a system, device, subscriber unit,subscriber station, mobile station, mobile, mobile device, remotestation, remote terminal, access terminal, user terminal, terminal,communication device, user agent, user device, or user equipment (UE). Awireless terminal may be a cellular telephone, a satellite phone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, a computingdevice, or other processing devices connected to a wireless modem.Moreover, various aspects are described herein in connection with a basestation. A base station may be utilized for communicating with wirelessterminal(s) and may also be referred to as an access point, a Node B,evolved Node B (eNB), or some other terminology.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form.

The techniques described herein may be used for various wirelesscommunication systems such as CDMA, TOMA, FDMA, OFDMA, SC-FDMA and othersystems. The terms “system” and “network” are often usedinterchangeably. A CDMA system may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband-CDMA (W-CDMA) and other variants of CDMA. Further, cdma2000covers IS-2000, IS-95 and IS-856 standards. A TOMA system may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA system may implement a radio technology such as EvolvedUTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are partof Universal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) is a release of UMTS that uses E-UTRA, which employsOFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTEand GSM are described in documents from an organization named “3rdGeneration Partnership Project” (3GPP). Additionally, cdma2000 and UMBare described in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). Further, such wireless communicationsystems may additionally include peer-to-peer (e.g., mobile-to-mobile)ad hoc network systems often using unpaired unlicensed spectrums, 802.xxwireless LAN, BLUETOOTH and any other short- or long-range, wirelesscommunication techniques.

Various aspects or features will be presented m terms of systems thatmay include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems may includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches may also be used.

Additionally, in the subject description, the word “exemplary” is usedto mean serving as an example, instance, or illustration. Any aspect ordesign described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other aspects or designs.Rather, use of the word exemplary is intended to present concepts in aconcrete fashion.

FIG. 1 shows a wireless communication system 100, which may be a 3GPPLTE E-UTRA system. System 100 may include base stations 110 and othernetwork entities described by 3GPP. A base station may be a fixedstation that communicates with the access terminals. Each base station110 may provide communication coverage for a particular geographic area.To improve network capacity, the overall coverage area of a base stationmay be partitioned into multiple (e.g., three) smaller areas. Eachsmaller area may be served by a respective base station subsystem. In3GPP, the term “cell” can refer to the smallest coverage area of a basestation and/or a base station subsystem serving this coverage area.

A system controller 130 may include a mobility management entity (MME)and a serving gateway (S-GW), and may couple to a set of base stationsand provide coordination and control for these base stations. S-GW maysupport data services such as packet data, Voice-over-Internet Protocol(VoIP), video, messaging, etc. MME may be responsible for path switchingbetween a source base station and a target base station at handover.System controller 130 may couple to a core and/or data network (e.g.,the Internet) and may communicate with other entities (e.g., remoteservers and terminals) coupled to the core/data network.

Access terminals 120 may be dispersed throughout the network, and eachaccess terminal may be stationary or mobile. An access terminal maycommunicate with a base station via downlink and uplink. The downlink(or forward link) refers to the communication link from the base stationto the access terminal, and the uplink (or reverse link) refers to thecommunication link from the access terminal to the base station. In FIG.1, a solid line with double arrows indicates active communicationbetween a base station and an access terminal.

FIG. 2 illustrates a system 200 including an uplink 212 and a downlink214 between a base station 204 and an access terminal 208. The basestation 204 and the access terminal 208 may correspond to the basestation 110 and the access terminal 120 shown in FIG. 1. The uplink 212refers to transmissions from the access terminal 208 to the base station204; and the downlink 214 refers to transmissions from the base station204 to the access terminal 208.

FIG. 3 illustrates some aspects of a protocol stack for a communicationssystem. Both, the base station 204 and the access terminal 208 mayinclude the protocol stack 300 illustrated in FIG. 3. The protocol stackmay include a physical layer (PHY) 316, a Medium Access Control (MAC)318, and higher layers 320.

The MAC layer 318 may receives data from the higher layers 320 via oneor more logical channels 322. The MAC layer 318 may then perform variousfunctions such as mapping between logical channels 322 and transportchannels 324, multiplexing and demultiplexing of various PDUs forlogical channels 322 into/from transport blocks for transport channels324, error correction, traffic volume measurement reporting, priorityhandling between logical channels 322 of an access terminal, priorityhandling between access terminals via dynamic scheduling, transportformat selection, padding, etc.

The physical layer 316 may be configured to provide multiple physicalcontrol channels 326. The access terminal 204 may be configured tomonitor this set of control channels. The physical layer 316 may alsooffer data transport services via the physical channels 326. Some thephysical channels for downlink signal transmissions may be PhysicalDownlink Control Channel (PDCCH), Physical Hybrid ARQ Indicator Channel(PHICH), and Physical Downlink Shared Channel (PDSCH). Some of thephysical channels for uplink signal transmissions may be Physical UplinkControl Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), andPhysical Random Access Channel (PRACH).

The system 100 may use orthogonal OFDMA for the downlink and SC-FDMA forthe uplink. The basic idea underlying OFDM is the division of theavailable frequency spectrum into several subcarriers. To obtain a highspectral efficiency, the frequency responses of the subcarriers areoverlapping and orthogonal. In the system 100, the OFDMA downlinktransmissions and the uplink transmissions may be organized into radioframes with a 10 ms duration. The frame structure may be applicable toboth frequency division duplex (FDD) (the application offrequency-division multiplexing to separate outward and return signals)and time division duplex (TDD) (the application of time-divisionmultiplexing to separate outward and return signals). As shown in FIG.4, each radio frame is 10 ms long and consists of 20 slots of 0.5 ms,numbered from 0 to 19. A subframe is defined as two consecutive slotswhere subframe i consists of slots 2 i and 2 i+1. The subframe may bereferred to as a transmission time interval (TTI). For FDD, 10 subframesare available for downlink transmission and 10 subframes are availablefor uplink transmissions in each 10 ms interval. Uplink and downlinktransmissions are separated in the frequency domain. For TDD, a subframeis either allocated to downlink or uplink transmission. Subframe 0 andsubframe 5 may always be allocated for downlink transmission.

The signal in each slot may be described by a resource grid of N_(SC)^(RB) subcarriers and N_(SYMB) symbols, which may be OFDM symbols fordownlink or SC-FDMA symbols for uplink. In case of multi-antennatransmission from the base station 110, there may be one resource griddefined per antenna port. An antenna port may be defined by a downlinkreference signal (DLRS) that is unique within the cell. Each element inthe resource grid for an antenna port p may be called a resource elementand is uniquely identified by the index pair (k,l) where k and l are theindices in the frequency and time domains, respectively. One, two, four,or more antenna ports may be supported. A physical resource block may bedefined as N_(SYMB) consecutive symbols in the time domain and N_(SC)^(RB) (e.g., 12) consecutive subcarriers in the frequency domain. Aresource block thus consists of N_(SYMB)×N_(SC) ^(RB) resource elements.

Data transmitted over the system 100 may be categorized as eithernon-real-time (NRT) data or real-time (RT) data. Examples of NRT datainclude data transmitted during web browsing by an access terminal ortext-messaging to an access terminal, while an example of RT data isvoice communication between access terminals.

Data packets (both NRT and RT) are transmitted from the base station tothe access terminals in the PDSCH. Various modulation and coding schemes(MCSs) are supported on the PDSCH. Modulation schemes include quadraturephase-shift keying (QPSK) and quadrature amplitude modulation (QAM),such as 16-QAM and 64-QAM. Various coding rates, used for errorcorrection, may be used. The combination of modulation schemes andcoding rates may result in a large number, e.g., 30, of possible MCSs.

In LTE based systems (e.g., 3GPP Release 8), uplink power control can bea combination of open loop power control and closed loop power control.With open loop power control, access terminal estimates downlink pathloss to facilitate power control. With closed loop, the base station canexplicitly control uplink transmit power via power control commands.Transmission and power control signaling in the absence of uplink datamay take place on the PUCCH; and control signaling in the presence ofuplink data may take place on the PUSCH.

FIG. 5 is an example of a multicarrier system that facilitates uplinkpower control in a wireless communication environment. As shown in FIG.5, multicarrier system 500 may include uplink carriers UL C1 506, UL C2508 and downlink carriers DL C1 510, DL C2 512, DL C3 514 between a basestation 502 and an access terminal 504. The base station 502 and theaccess terminal 504 may correspond to the base station 110 and theaccess terminal 120 shown in FIG. 1. The system 500 is shown to beasymmetric in the sense that the number of uplink carriers 506, 508 isnot equal to the number of downlink carriers 510, 512, 514. Althoughonly two uplink carriers and three downlink carriers are shown, thesystem 500 may be configured to include any number of uplink anddownlink carriers. The system 500 may also be a symmetric system havingan equal number uplink and downlink carriers.

The system 500 is further configured to support carrier pairing betweenthe uplink and downlink carriers. The pairing can be between one or moredownlink carriers and one or more uplink carriers. In one configuration,at least one downlink carrier is paired with a plurality of uplinkcarriers or a plurality of downlink carriers are paired with at leastone uplink carrier, such that the pairing group of downlink and uplinkcarriers contains at least three carriers.

The system 500 man include any number of disparate base stations similarto the base station 502 and/or any number of disparate access terminalssimilar to access terminal 504. According to an illustration, system 500can be a LTE-A based system; however, the claimed subject matter is notso limited.

To facilitate multicarrier operations, system 500 can provide powercontrol on a per carrier basis. Per carrier power control enablesoperations in separate frequency bands as well flexibility forinterference management purposes.

In an aspect, access terminal 504 may determine transmit power for datatransmission on PUSCH. According to an example, transmission powerP_(PUSCH)(i,k), in dBm, for a plurality of carriers indicated by carrierindex k, in subframe i, can be determined by the following Equation 1:P _(PUSCH)(i,k)=min{P _(MAX),10 log₁₀(M _(PUSCH)(i,k))+P _(O) _(_)_(PUSCH)(j,k)+a(j,k)·PL(k)+Δ_(TF)(i,k)+f(i,k)}

Pursuant to this illustration, all components are defined per uplinkcarrier, as specified by carrier index k. In Equation 1, P_(MAX) is amaximum allowed transmission power, as configured in higher layers(e.g., in system information blocks (SIB)). M_(PUSCH)(i,k) is thebandwidth of a PUSCH resource assignment expressed in a number ofresource blocks valid for subframe i. P_(O) _(_) _(PUSCH)(j,k) is aparameter configured by the sum of 8-bit cell specific nominal componentand a 4-bit access terminal specific component, and is provided byhigher layers for both j=0 and j=1. a(j,k) is a 3-bit cell specificparameter provided by a higher layer that weighs the effect of path lossestimates in power control decisions. PL(k) is a downlink path lossestimate calculated in the access terminal. In one example, the pathloss estimate is based upon a difference between a reference signalpower as provided by higher layers and a higher layer filtered referencesignal received power. Δ_(TF)(i,k) is a power offset particular to aspecific transport format of information and/or a specific modulationand coding scheme. Δ_(TF)(i,k) can be provided by 10log₁₀(2^((MPR)(Ks)−1)), where Ks is given by deltaMCS-Enabled, aparameter specific to an access terminal provided by higher layers, andwhere MPR=TBS/N_(RE), TBS being the transport block size and N_(RE)being a number of resource elements. The parameter f(i,k) is a powercontrol adjustment state as provided by the base station and isdetermined by δ_(PUCCH), an access terminal correction value referred toas a Transmission Power Control (TPC) command. δ_(PUCCH) is the TPCinformation transmitted from the base station to the access terminal viathe PDCCH or the PDSCH.

In an aspect, access terminal 504 may also determine transmit power fordata transmission on PUCCH. According to an example, the transmissionpower P_(PUCCH)(i,k) of a signal transmitted through uplink via thePUCCH in the subframe i for a plurality of earners, as indicated by thecarrier index k, may be determined by the following Equation 2:P _(PUSCH)(i,k)=min{P _(MAX) P _(O) _(_) _(PUCCH,k) +PL(k)+h(n _(CQI) ,n_(HARQ) ,k)+Δ_(F) _(_) _(PUCCH)(TF,k)+g(i,k)}

Pursuant to this illustration, all components are defined per unitcarrier, as specified by carrier index k. Δ_(F) _(_) _(PUCCH)(TF, k)with respect to each PUCCH transport format (TF) is provided by an RRC.P_(O) _(_) _(PUCCH,k) is a parameter configured by the sum of a 5-bitcell specific parameter provided by a higher layer and an accessterminal specific component given by the RRC. is a factor determined byδ_(PUCCH), also a TPC command. δ_(PUCCH) is TPC information transmittedfrom the base station to the access terminal via the PDCCH or the PDSCH.

Power control commands (e.g., TPC) can be generated and signaled by thebase station 502. Power control commands for PUSCH may be included inuplink grants, while power control commands for PUCCH may be conveyed indownlink grants. In addition, the base station 502 can convey powercontrol commands for a group of access terminals utilizing DownlinkControl Information (DCI). DCI formats 3 and 3A may be used for PUCCHand PUSCH with 2-bit or 1-bit power adjustments for each carrier,respectively. In the multicarrier system 500, multicarrier uplink and/ordownlink grants may carry access terminal TPC commands for allconfigured access terminals, and may be transmitted by the base station502 on any downlink carrier. The access terminal 504 may monitor one ora multitude of downlink carriers (e.g., anchor carrier) for themulticarrier grants. The base station 502 may use Radio Resource Control(RRC) signaling to inform the access terminal 504 which downlinkcarriers to monitor for possible grants.

FIG. 6 shows is a block diagram illustrating an example ofdownlink/uplink carrier pairing for the system 500. As shown in FIG. 6,UL C1 506 may be paired with DL C1 510 (shown with solid arrow 602), andUL C2 508 may be paired with DL C2 512 and DL C3 514 (shown with solidarrows 604, 606). UL C1 506 may receive uplink control information forDL C1 510, and UL C2 508 may receive uplink control information for DLC2 512 and DL C3 514. The uplink control information may includedownlink Hybrid Automatic Repeat Request (HARQ) feedback and ChannelQuality Indicator (CQI) feedback. Similarly, the DL C1 may receivedownlink control information for UL C1 506, and DL C2 512 and DL C3 514may receive downlink control information for UL C2 508. The downlinkcontrol information may include uplink grants, downlink grants, as wellas uplink HARQ feedback.

Carrier pairing can be semi-static or dynamic as determined by the basestation 502. For semi-static pairing, the base station 502 can notifyall the access terminals 504, 120 of the pairing by broadcasting thesystem information in a SIB. Alternatively, the base station 502 caninform each access terminal 504, 120 of the pairing with a dedicatedsignaling through RRC signaling in an RRC connection setup message. Fordynamic pairing, the base station 110 can notify the access terminals120 of the pairing through MAC signaling included in the grant message.

The carrier on which control information is sent may also depend onwhether there are any designated anchor carriers. If an anchor carrieris present in the system, control information may be sent on the anchorcarrier for one or more of the corresponding carriers, even if thecarriers are outside the pairing. For example, if DL C1 510 may bedesignated as the anchor carrier for the downlink carriers 510, 512,514, and UL C1 506 may be designated as the anchor carrier for theuplink carriers 506, 508, then UL C1 506 would receive controlinformation for downlink carriers 510, 512, 514, and DL C1 510 wouldreceive control information for uplink carriers 506, 508.

One or more anchor carriers can be defined for each of the uplinkcarriers and the downlink carriers. The base station 502 may notify theaccess terminals 504, 120 of an anchor carrier in an SIB or through adedicated signaling such as RRC signaling. The base station 502 notifiesaccess terminals 504, 120 of the uplink/downlink pairing and any anchorcarriers in SIBs. The SIBs may include carrier locations (i.e., carriercenter frequencies), carrier bandwidths, carrier designation(uplink/downlink), carrier pairing, and anchor carrier information, aswell as on which specific carrier and resources to expectuplink/downlink grants carrying TPC commands. In one configuration, someof the control information may be sent through the anchor carrier andother control information may be sent through the paired carrier. Forexample, the base station 110 could indicate with a flag through abroadcast or RRC signaling whether the uplink TPC command will be senton a paired downlink carrier or the designated downlink anchor carrier.

Base station 502 may also analyze a power headroom report provided byaccess terminal 504. The power headroom report indicates a differencebetween maximum transmission power available to the access terminal 504and a transmission power that would be utilized for a carrier (or atotal of all carriers). In this manner, the base station 502 mayestimate the power limitations of the access terminal 504. The basestation 502 may also facilitate generation of power control commandsand/or facilitate scheduling decisions. For instance, the base station502 may identify situations where the access terminal 504 should not bescheduled on multiple carriers when the access terminal 504 cannotsupport the carriers.

In another aspect, the base station 502 can employ overload indicators.An overload indicator per carrier provides better control in cases whencarriers are not uniformly loaded and shared. For example, in case of anasymmetric carrier configuration, as illustrated in the system 500,whether one or a plurality of downlink carriers may carry the overloadindicator depends on they type of carrier asymmetry. If the number ofuplink carriers is greater than the number of downlink carriers, thenonly one downlink carrier would carry the overload indicator for thecorresponding uplink carriers based on the uplink/downlink carrierpairing. If on the other hand, the number of uplink carriers is lessthan the number of downlink carriers, more than one downlink carriercould carry the overload indicator for the corresponding uplink based onthe uplink/downlink pairing. Overload indicators may also be transmittedon anchor carriers regardless of the uplink/downlink carrier pairing.

In another aspect, access terminal 504 may facilitate configuration ofuplink transmission power for each uplink carrier. In one example, theaccess terminal 504 may distribute power over multiple carriers. Forinstance, the access terminal 504 may prioritize carriers such thatnecessary power is provided according to importance of carriers. In oneexample, anchor carriers may have higher priority than other carriers,and thus, may receive required power first. In another example, uplinkcarriers carrying the highest priority data may have higher prioritythan other carriers, and thus, may receive required power first.Alternatively, a prioritization list indicating carrier priority may beconveyed to the access terminal 504 by the base station 502. The accessterminal 504 may also uniformly scale power across the carriers.Further, the base station 502 and/or the access terminal 504 may beconfigured to fulfill PUCCH power requirements before PUSCH powerrequirements, on any given carrier. If, however, control information orupper layer signaling is transmitted on a PUSCH of a high prioritycarrier, the base station 502 and/or the access terminal 504 willaccommodate such PUSCH power requirements on the high priority carrierbefore the PUCCH power requirements of carriers with lower priority.

FIG. 7 is an illustration of an access terminal that facilitates uplinkpower control in a multicarrier communications system. The accessterminal 700 may correspond to the one of the access terminals 120 shownin FIG. 1. As shown in FIG. 7, the access terminal 700 may include areceiver 702 that receives multiple signals from, for instance, one ormore receive antennas (not shown), performs typical actions on (e.g.,filters, amplifies, downconverts, etc.) the received signals, anddigitizes the conditioned signals to obtain samples. The receiver 702may include a plurality of demodulators 704 that can demodulate receivedsymbols from each signal and provide them to a processor 706 for channelestimation, as described herein. The processor 706 can be a processordedicated to analyzing information received by the receiver 702 and/orgenerating information for transmission by a transmitter 716, aprocessor that controls one or more components of the access terminal700, and/or a processor that both analyzes information received by thereceiver 702, generates information for transmission by the transmitter716, and controls one or more components of the access terminal 700.

The access terminal 700 may additionally include memory 708 that isoperatively coupled to the processor 706 and that can store data to betransmitted (e.g., high priority data), received data, informationrelated to available channels, data associated with analyzed signaland/or interference strength, information related to an assignedchannel, power, rate, or the like, and any other suitable informationfor estimating a channel and communicating via the channel. Memory 708can additionally store protocols and/or algorithms associated withestimating and/or utilizing a channel (e.g., performance based, capacitybased, etc.).

It will be appreciated that the data store (e.g., memory 708) describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable PROM (EEPROM), or flash memory. Volatile memorycan include random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).The memory 708 of the subject systems and methods is intended tocomprise, without being limited to, these and any other suitable typesof memory.

The receiver 702 can further be operatively coupled to a controller 710that can control uplink power for a plurality of uplink carriers bydecoding power control commands for the plurality of carriers, anddistributing power among the plurality of carriers based on the powercontrol commands. The controller can further control the acquisition andstorage in memory 708 of the power control commands, and directcommunications with the base station by interfacing with transmitter 714via the processor 706, as discussed with reference to FIG. 1. The accessterminal 700 still further comprises a modulator 712 that modulates andtransmits signals via transmitter 714 to, for instance, a base station,a web/internet access point name (APN), and another access terminal,etc. Although depicted as being separate from the processor 706, it isto be appreciated that the controller 710, demodulators 704, and/ormodulator 712 can be part of the processor 706 or multiple processors(not shown). Furthermore, the functions of the controller 710 may beintegrated in an application layer, a data stack, an HTTP stack, at theoperating system (OS) level, in an internet browser application, or inan application specific integrated circuit (ASIC).

FIG. 8 is an illustration of a system 800 that controls feedback in anasymmetric multicarrier communications system. The system 800 comprisesa base station 802 (e.g., access point, femtocell, etc.) with a receiver810 that receives signal(s) from one or more access terminals 804through a plurality of receive antennas 806, and a transmitter 824 thattransmits to the one or more access terminals 804 through a transmitantenna 808. Receiver 810 can receive information from receive antennas806 and is operatively associated with a demodulator 812 thatdemodulates received information. Demodulated symbols are analyzed by aprocessor 814 that can perform some or all functions for the basestation 808 described above with regard to FIG. 1, and which is coupledto a memory 816 that stores information related to estimating a signal(e.g., pilot) strength and/or interference strength, data to betransmitted to or received from mobile device(s) 804 (or a disparatebase station (not shown)), and/or any other suitable information relatedto performing the various actions and functions set forth herein.Processor 814 is further coupled to a controller 818 that can controluplink power on a plurality of uplink carriers by determining the powerrequired for the plurality of carriers, and generating power controlcommands for the plurality of carriers based on the determination.Although depicted as being separate from the processor 814, it is to beappreciated that the controller 818, demodulator 812, and/or modulator820 can be part of the processor 814 or multiple processors (not shown).

FIG. 9 is a flow chart illustrating an example of a process for uplinkpower control in a multicarrier communications system. The process maybe implemented in the access terminals 120 of system 100. As shown inFIG. 9, in block 902, power control commands may be decoded for at leastone of a plurality of carriers, and the process may proceed to block904. For example, the access terminal 120 may receive a power controlcommands from base station 110 on a single downlink carrier, and decodethe power control commands.

In block 904, power among the at least one of the plurality of carriersmay be distributed based on the power control commands, and the processmay end. For example, the access terminal 120 may distribute and/oradjust the power among the plurality of carriers according to the powercontrol commands received from the base station 110.

FIG. 10 is a flow chart illustrating an example of a process for uplinkpower control in a multicarrier communications system. The process maybe implemented in the base station 110 of system 100. As shown in FIG.10, in block 1002, power required for at least one of a plurality ofcarriers may be determined, and the process may proceed to block 1004.For example, the base station 110 may receive a power headroom reportfrom access terminal 120, and based on the headroom report determine thepower required for the plurality of uplink carriers.

In block 1004, at least one of a plurality of power control commands forthe at least one of the plurality of carriers may be generated based onthe determination, and the process may end. For example, the basestation 110 may generate and transmit power control commands for theplurality of uplink carriers to the access terminal 120 based on thepower requirements of the access terminal 120.

FIG. 11 is an illustration of an example system 1100 that facilitatesuplink power control in a multicarrier communications system. Forexample, system 1100 can reside at least partially within an accessterminal, etc. It is to be appreciated that system 1100 is representedas including functional blocks, which can be functional blocks thatrepresent functions implemented by a processor, software, or combinationthereof (e.g., firmware). System 1100 includes a logical grouping 1102of means that can act in conjunction. For instance, logical grouping1102 can include: means for decoding power control commands for at leastone of a plurality of carriers 1104; and means for distributing poweramong the at least one of the plurality of carriers based on the powercontrol commands 1106. Additionally, system 1100 can include a memory1108 that retains instructions for executing functions associated withthe means 1104 through 1106. While shown as being external to memory1108, it is to be understood that one or more of the means 1104 through1106 can exist within memory 1108.

FIG. 12 is an illustration of an example system 1200 that facilitatesuplink power control in a multicarrier communications system. Forexample, system 1200 can reside at least partially within a basestation, etc. It is to be appreciated that system 1200 is represented asincluding functional blocks, which can be functional blocks thatrepresent functions implemented by a processor, software, or combinationthereof (e.g., firmware). System 1200 includes a logical grouping 1202of means that can act in conjunction. For instance, logical grouping1202 can include: means for determining power required for at least oneof a plurality of carriers 1204; and means for generating at least oneof a plurality of power control commands for at least one of theplurality of carriers based on the determination 1206. Additionally,system 1200 can include a memory 1208 that retains instructions forexecuting functions associated with the means 1204 through 1206. Whileshown as being external to memory 1208, it is to be understood that oneor more of the means 1204 through 1206 can exist within memory 1208.

The various illustrative logics, logical blocks, modules, and circuitsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but, in the alternative, the processor may be any conventionalprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Additionally, at least oneprocessor may comprise one or more modules operable to perform one ormore of the steps and/or actions described above.

Further, the steps and/or actions of a method or algorithm described inconnection with the aspects disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of storage mediumknown in the art. An exemplary storage medium may be coupled to theprocessor, such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. Further, in some aspects, theprocessor and the storage medium may reside in an ASIC. Additionally,the ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal. Additionally, in some aspects, the steps and/or actionsof a method or algorithm may reside as one or any combination or set ofcodes and/or instructions on a machine readable medium and/or computerreadable medium, which may be incorporated into a computer programproduct.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored or transmitted as one or moreinstructions or code on a computer-readable medium. Computer-readablemedia includes both computer storage media and communication mediaincluding any medium that facilitates transfer of a computer programfrom one place to another. A storage medium may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionmay be termed a computer-readable medium. For example, if software istransmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While the foregoing disclosure discusses illustrative aspects and/orembodiments, it should be noted that various changes and modificationscould be made herein without departing from the scope of the describedaspects and/or embodiments as defined by the appended claims.Furthermore, although elements of the described aspects and/orembodiments may be described or claimed in the singular, the plural iscontemplated unless limitation to the singular is explicitly stated.Additionally, all or a portion of any aspect and/or embodiment may beutilized with all or a portion of any other aspect and/or embodiment,unless stated otherwise.

What is claimed is:
 1. A method for wireless communication, comprising:receiving, by a user equipment (UE), a flag indicating that a schedulinggrant comprising a power control command for an uplink carrier of aplurality of uplink carriers configured for the UE is to be transmittedon one of either a first downlink carrier paired with the uplink carrieror an anchor carrier that is not paired with the uplink carrier;receiving the power control command for the uplink carrier as part ofthe scheduling grant based on the received flag; and adjusting atransmission power of the UE for a transmission on the uplink carrierbased on the power control command.
 2. The method of claim 1, furthercomprising: determining the transmission power for the transmission on aphysical uplink shared channel (PUSCH) of the uplink carrier based onthe received power control command.
 3. The method of claim 2, whereindetermining the transmission power comprises fuflilling physical uplinkcontrol channel (PUCCH) power requirements before PUSCH powerrequirements of the uplink carrier.
 4. The method of claim 1, furthercomprising: receiving a connection setup message comprising anindication that the first downlink carrier is paired with the uplinkcarrier.
 5. The method of claim 1, wherein adjusting the transmissionpower comprises distributing power among the plurality of carriers basedon the received power control command.
 6. The method of claim 1, whereinthe power control command comprises a plurality of power controlcommands for the plurality of uplink carriers.
 7. The method of claim 6,wherein the plurality of power control commands are received on onecarrier.
 8. The method of claim 1, wherein the power control command isfor the plurality of uplink carriers.
 9. The method of claim 1, furthercomprising: receiving an overload indicator indicating an overload ofthe uplink carrier on the first downlink carrier that is paired with theuplink carrier.
 10. The method of claim 1, further comprising: receivingan overload indicator indicating an overload of the uplink carrier onthe anchor carrier irrespective of carrier pairing.
 11. The method ofclaim 1, further comprising: prioritizing power distribution among theplurality of carriers based on a carrier priority of each one of theplurality of carriers.
 12. The method of claim 11, wherein an uplinkanchor carrier has higher carrier priority than other uplink carriers inthe plurality of uplink carriers.
 13. The method of claim 11, furthercomprising: receiving a prioritization list indicating the carrierpriority for the plurality of carriers.
 14. The method of claim 1,further comprising: prioritizing power distribution among the pluralityof uplink carriers based on a channel priority of each one of theplurality of uplink carriers.
 15. The method of claim 14, wherein thechannel priority of each one of the plurality of uplink carriers isdetermined based on whether control data is transmitted across a channelof a respective one of the plurality of uplink carriers.
 16. The methodof claim 1, further comprising: receiving at least one weightingparameter for weighting path loss estimates in performing power controlfor the uplink carrier of the plurality of uplink carriers.
 17. Themethod of claim 1, wherein the flag indicating that the scheduling grantfor the uplink carrier is to be transmitted on either the first downlinkcarrier or the anchor carrier is received via radio resource control(RRC) signaling.
 18. The method of claim 1, wherein the scheduling grantcomprises an uplink grant comprising the power control command for anuplink data channel of the uplink carrier.
 19. The method of claim 1,wherein the scheduling grant comprises a downlink grant comprising thepower control command for an uplink control channel of the uplinkcarrier.
 20. An apparatus comprising: means for receiving, by a userequipment (UE), a flag indicating that a scheduling grant comprising apower control command for an uplink carrier of a plurality of uplinkcarriers configured for the UE is to be transmitted on one of either afirst downlink carrier paired with the uplink carrier or an anchorcarrier that is not paired with the uplink carrier; means for receivingthe power control command for the uplink carrier as part of thescheduling grant based on the received flag; and means for adjusting atransmission power of the UE for a transmission on the uplink carrierbased on the power control command.
 21. The apparatus of claim 20,further comprising: means for determining the transmission power for thetransmission on a physical uplink shared channel (PUSCH) of the uplinkcarrier based on the received power control command.
 22. The apparatusof claim 20, further comprising: means for distributing power among theplurality of carriers based on the received power control command. 23.The apparatus of claim 20, further comprising: means for receiving anoverload indicator indicating an overload of the uplink carrier on thefirst downlink carrier that is paired with the uplink carrier.
 24. Theapparatus of claim 20, further comprising: means for prioritizing powerdistribution among the plurality of carriers based on a carrier priorityof each one of the plurality of carriers.
 25. A computer programproduct, comprising a non-transitory computer-readable medium, thenon-transitory computer-readable medium comprising: code for receiving,by a user equipment (UE), a flag indicating that a scheduling grantcomprising a power control command for an uplink carrier of a pluralityof uplink carriers configured for the UE is to be transmitted on one ofeither a first downlink carrier paired with the uplink carrier or ananchor carrier that is not paired with the uplink carrier; code forreceiving the power control command for the uplink carrier as part ofthe scheduling grant based on the received flag; and code for adjustinga transmission power of the UE for a transmission on the uplink carrierbased on the power control command.
 26. The computer program product ofclaim 25, further comprising: code for determining the transmissionpower for the transmission on a physical uplink shared channel (PUSCH)of the uplink carrier based on the received power control command. 27.The computer program product of claim 25, further comprising: code fordistributing power among the plurality of carriers based on the receivedpower control command.
 28. The computer program product of claim 25,further comprising: code for receiving an overload indicator indicatingan overload of the uplink carrier on the first downlink carrier that ispaired with the uplink carrier.
 29. The computer program product ofclaim 25, further comprising: code for prioritizing power distributionamong the plurality of carriers based on a carrier priority of each oneof the plurality of carriers.
 30. A wireless communication apparatus,comprising: a processor; a memory storing instructions, the instructionsexecutable by the processor to: receive, by a user equipment (UE), aflag indicating that a scheduling grant comprising a power controlcommand for an uplink carrier of a plurality of uplink carriersconfigured for the UE is to be transmitted on one of either a firstdownlink carrier paired with the uplink carrier or an anchor carrierthat is not paired with the uplink carrier; receive the power controlcommand for the uplink carrier as part of the scheduling grant based onthe received flag; and adjust a transmission power of the UE for atransmission on the uplink carrier based on the power control command.